1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus.
2. Related Art
In the related art, as an example of an ink jet type recording head which is a representative example of a liquid ejecting head to eject liquid drops, there is an ink jet type recording head which includes a flow path forming substrate in which plural pressure generating chambers are formed, piezoelectric actuators which are provided to correspond the respective pressure generating chambers on one surface of the flow path forming substrate, and a nozzle plate which is provided on the other surface of the flow path forming substrate and provides nozzle holes to communicate pressure generating chambers, and applies pressure to each pressure generating chamber by displacement of each piezoelectric actuator to eject ink drops from the nozzle holes.
In this manner, the ink drops are ejected from the nozzle hole so that for example, a hydrophilic film is formed in the nozzle hole to improve ejection characteristics of liquid. That is, the hydrophilic film is formed in the nozzle hole to increase wettability for ink. Thus, bubbles generated in the nozzle hardly adhere to an inner wall of the nozzle hole so that ink ejection defects in the nozzle hole are suppressed and ejection characteristics can be improved.
When the hydrophilic film is formed in such a nozzle hole, a water repellent film formation on an ejection surface of the nozzle plate is further known (refer to JP-A-2005-161679 (Claim 1 and the like)). In this case, the water repellent film is formed by plating so that the water repellent film is formed in a part of the ejection surface of the inner wall in the nozzle hole which is a through hole. By forming the water repellent film in this manner, ink does not adhere to the part, and unevenness in an ejection direction and ejection velocity of ink drop is suppressed.
However, in the structure disclosed in JP-A-2005-161679 (Claim 1 and the like), since the entire inner wall of the nozzle hole is hydrophilic and the inner wall has high wettability for ink. Therefore there is a problem that a large pressure is required when a meniscus moves in the nozzle hole to a vertical direction at the time of ejecting the ink. As described above, since the inner wall has high wettability for ink, the meniscus disposed on the inner wall at the time of ejecting the ink is easily influenced by the inner wall. Thus, there is a problem that flight deflection easily occurs.
Even when the water repellent film is formed only around an opening of the nozzle hole, the meniscus is finally disposed on a surface having high wettability for ink where the hydrophilic film is formed. Thus, it is considerable that a large pressure is required when a meniscus moves in the nozzle hole to the vertical direction at the time of ejecting the ink to lower ejection efficiency and flight deflection occurs and thereby liquid ejection characteristics are lowered.